1. Field of the Invention
The present invention relates to a liquid ejecting device. In particular, the present invention relates to a liquid ejecting device that can remove air bubbles that are generated in a liquid flow path.
2. Description of the Related Art
In inkjet printers, air bubbles that arise at an ejecting head that ejects ink are a cause of non-ejecting of the ink. Further, in a device that circulates ink in pipes of a circulating system and supplies ink to an ejecting head, there are cases in which air bubbles exist not only in the ejecting head, but within the ink path as well. In such cases, the flow path resistance increases, and ink cannot be supplied sufficiently to the ejecting head. Moreover, in the case of a device that uses an elongated ejecting head as the ejecting head, the ink path is long and the shape of the circulating path is complex. Therefore, the flow path resistance is large, and is difficult to trap and remove the air bubbles. Accordingly, in such a device, removal of air bubbles is necessary not only within the elongated head, but at the entire ink supply path as well.
Japanese Patent Application Laid-Open (JP-A) No. 3-234651 (document 1), JP-A No. 3-274165 (document 2), JP-A No. 2-179757 (document 3) and JP-A No. 3-293152 (document 4), that will be described hereinafter, are known as techniques for removing air bubbles.
In the devices disclosed in document 1, document 2 and document 3, a recording head (ejecting head) and an ink supply tank are connected by a supply pipe and a circulating pipe. At the time of the recording operation, the device supplies ink from the ink supply tank to the recording head through the supply pipe. At the time of the recovery operation, the device uses a recovery pump to send the ink through the circulating path to the recording head from the direction opposite the ink flowing direction at the time of the recording operation, and carries out bubble removal and the like.
Further, in the device disclosed in document 4, the recording head and an ink storage tank are connected by a supply pipe and a return pipe. A valve, a mesh filter, a waste ink tank and a pump are provided at the supply pipe. The pressure-feeding direction of the ink that is pressure-fed by the pump is reversed at times of a usual recovery operation and times of a non-ejecting recovery operation. Due thereto, in this device, foreign matter is caught at the valve side of the mesh filter at times of the usual recovery operation, whereas, at times of the non-ejecting recovery operation, the trapped foreign matter is pulled apart from the mesh filter and, together with ink, flows into the waste ink tank.
However, in the devices disclosed in documents 1 to 3, at times of the recovery operation (bubble removal), ink is pressure-fed only in one direction with respect to the circulating path. In pressure-feeding the ink in the one direction, the way that the ink flows within the path is limited, and therefore, there exist air bubbles that cannot be completely captured in light of the structure of the path. Further, in the device disclosed in document 4, the ink is pressure-fed in both directions with respect to the circulating path, and the ink that is pressure-fed from the recording head is returned to the supply tank and a portion thereof is subjected to waste liquid treatment. However, this treatment is for the purpose of preventing clogging of the filter, and removal of air bubbles that are within the circulating path cannot be carried out. Moreover, in the devices disclosed in documents 1 and 4, when removing air bubbles that are within the path, ink is wasted because ink that includes air bubbles is discharged from the nozzles for ink ejection. In addition, when the ink that includes air bubbles is not discharged from the nozzles, ink that includes air bubbles and ink that does not include air bubbles mix together within the supply tank. As a result, ink that contains air bubbles is again supplied to the ejecting head.